Stability, enhancement of elastic properties and structure of multilayered amorphous carbon films

The growth of sputtered amorphous carbon a-C.films in layer structure with alternating negativerpositive.substrate bias voltage Vb, was applied to control their intrinsic stress level and stability. The main benefit of the process was the development of thick, stable, hard and rich in sp3 sites films proving their usefulness for many practical applications. In order to investigate the structure and the mechanisms of film stability we performed in-situ Spectroscopic Ellipsometry, Stress, Nanoindentation, Raman and Transmission Electron Microscopy TEM.measurements. The latter provides details about the layered structure of the films. A stress relief was found to occur in films depending on the sequence of layers and their modulation period. Despite the film stability an improvement in film hardness and elastic modulus was also achieved, whereas nanocrystalline carbon phases were detected and identified by Raman spectra. q1999 Elsevier Science B.V. All rights reserved